CubeSats have not required thermal control outside of resistive heaters due to low power requirement and a short lifespan. However, in the past few years, CubeSat form factor solar panels have been developed producing up to 80 W of power for a 3 U, i.e., a 30 by 30 by 10 cm, spacecraft. Furthermore, many CubeSat and small satellite missions, such as CeRES and LWaDi, are being proposed with high power instruments and subsystems on board. As a result, a thermal control louver assembly based on the CubeSat form factor has become critical for small spacecraft missions.
Previous designs for thermal louvers have been for full-sized spacecraft, which are several feet in diameter. These thermal louvers operate via metallic springs attached to flaps having a low-emissivity coating on the outside surface and high emissivity coating or direct view to the components underneath. When the components inside the spacecraft reach a high temperature, the bimetallic springs uncurl causing the flaps to open and change the emissivity of the spacecraft. However, thermal louvers for full-sized spacecraft cannot be used on a CubeSat or on small spacecraft. This is primarily due to the size of the thermal louvers.
In an effort to remedy this issue, an adaption of this technology for smaller spacecraft involved Micromachined Louver Arrays (MLAs), which were on a microscopic scale and actuated using electric current, i.e., an active means of louver actuation. However, this adaption requires an active control and a tendency for dust to accumulate inhibits the movement of the micro-scale flaps. Thus, an alternative approach may be beneficial.